It is a standard practice to use insulated bus bars in electrical equipment. High-power electrical distribution systems may suffer from corona discharge between conductors, which seriously degrades system performance, and may present a safety danger. This problem increases as the voltage levels increase and/or the physical separation between the conductors decrease.
In high-voltage electrical transmission, such as in long distance power transmission, corona discharge is reduced by spacing the conductors apart by large distances, as seen in high-tension electrical transmission towers. But this is not practical in closed environments, where inductive reactance must be minimized. Although close spacing of the conductors increases the tendency for corona discharge to occur in adjustable-speed devices, such close spacing improves system performance by reducing parasitic reactants.
To overcome the problems associated with closely spaced conductors, typical electrical distribution systems insulate the conductors or place insulation between adjacent conductors. As voltage levels increase, corona discharge increases, and the insulation degrades over time. Degradation of the insulation is dependent upon temperature, humidity, and voltage levels, and leads to corona discharge and further degradation of the insulation. Eventually, a short circuit may occur, which seriously affects system performance, and may pose a danger to human life.
Some known systems address this problem by eliminating the air between the conductors. This is accomplished by sealing the conductors in a chamber or conduit and evacuating the air. This method, however, is very expensive and is dependent upon the level of vacuum achieved, surface preparation of the conductors, and electrical braking cycles.